The greatest risk to construction workers is trench collapses, or cave-ins resulting in serious injury or death. if done properly, hazards can be effectively mitigated by implementing appropriate protective measures. Some of the main issues are training, worker exposure to other potential hazards including falls, falling loads, hazardous atmospheres, and mobile equipment accidents.
According to NIOSH (National Institute for Occupational Safety and Health), there were 137 fatalities attributed to excavation and trench cave-ins spanning a 7-year period that ended in 2018, equating to an annual rate of 20 incidents. OSHA standards require that employers provide workplaces free of recognized hazards. The employer must comply with the trenching and excavation requirements of 29 CFR 1926.651 and 1926.652 or comparable OSHA-approved state plan requirements.
In addition to outreach programs, safety summits, and online resources, OSHA provides employers with compliance guidance.
Workers who encounter trenches deeper than five feet without sloping, shoring, or shielding are encouraged to check with their employer’s management team to ensure a Competent Person is available to provide proper oversight or contact their local OSHA for support.
What is the OSHA 5-4-3-2-1 Rule?
5 feet deep trenches must have a protective system in place. Trenches greater than 4 feet must have a ladder for exit/egress. Ladders should extend at least 3 feet beyond the excavation for easy access and easy exit. Place excavated materials a minimum of 2 feet away from the edge of the excavation, 1 Competent Person is required to provide oversight.
5 Feet excavation with engineered protective system installed
What is a Competent Person?
OSHA standards require, before any worker entry, that employers have a competent person inspect trenches daily and as conditions change to ensure elimination of excavation hazards. A competent person is an individual who is capable of identifying existing and predictable hazards or working conditions that are hazardous, unsanitary, or dangerous to workers, soil types and protective systems required, and who is authorized to take prompt corrective measures to eliminate these hazards and conditions.
What steps can be implemented to ensure safety during trenching activities?
• Keep heavy equipment away from trench edges.
• Identify other sources that might affect trench stability.
• Keep excavated soil (spoils) and other materials at least 2 feet (0.6 meters) from trench edges.
• Know where underground utilities are located before digging.
• Test for atmospheric hazards such as low oxygen, hazardous fumes and toxic gases when > 4 feet deep.
• Inspect trenches at the start of each shift.
• Inspect trenches following a rainstorm or other water intrusion.
• Do not work under suspended or raised loads and materials.
• Inspect trenches after any occurrence that could have changed conditions in the trench.
• Ensure that personnel wear high visibility or other suitable clothing when exposed to vehicular traffic.
4-foot-deep trench with ladder extending 3-feet above for exit/egress.
What are some examples of Protective Systems?
In terms of protective systems, there are several types.
Benching means a method of protecting workers from cave-ins by excavating the sides of an excavation to form one or a series of horizontal levels or steps, usually with vertical or near- vertical surfaces between levels. Benching cannot be done in Type C soil as it is sandy and unstable.
Sloping involves cutting back the trench wall at an angle inclined away from the excavation.
Shoring requires installing aluminum hydraulic or other types of supports to prevent soil movement and cave-ins.
Shielding protects workers by using trench boxes or other types of supports to prevent soil cave-ins.
Designing a protective system can be complex as there are many factors. For example, soil classification, depth of cut, water content of soil, changes caused by weather or climate, surcharge loads (e.g., spoil, other materials to be used in the trench) and other operations in the vicinity.
2 feet from the edge of the excavation is clear of soil
What are the top 3 reasons that Access and Egress are important when digging?
Efficient access and egress facilitate quick evacuation in case of emergencies. In the event of an accident or entrapment, easy access and egress are essential for swift and effective rescue operations, increasing the probability of a positive outcome.
Well-designed access and egress systems are efficient and optimize workflow, enabling efficient movement of personnel and equipment, ultimately contributing to the overall productivity of trenching and excavation projects.
Adhering to access and egress guidelines ensures compliance with regulations, promoting a secure working environment and sustainability by avoiding costly losses or legal consequences.
A worker who did not have proper Access and Egress at the excavation required rescue
To ensure the safety and well-being of construction workers and the public, understanding the dangers of digging and actively safeguarding against them is essential. The risks associated with trenching and excavation activities are real and can have severe consequences. The use of proper training, the use of protective systems, and vigilant hazard identification can enable us to create a work environment that prioritizes safety. Education and a commitment to safety are essential to mitigating excavation hazards, leading to a safer and more secure construction industry.